1. Field of the Invention
The present invention generally relates to the art of bushings. In particular, the present invention relates to a jounce plate fastener retention system for a vehicle employing an oversized bushing that is used to create an interference fit with a fastener, thereby holding the fastener in place until the fastener and associated parts can be affixed to the vehicle or a mating vehicle part.
2. Description of the Related Art
Modular vehicle manufacturing has been used throughout the automotive industry over the past several years. This type of manufacturing strives to reduce the number and associated complexity of parts used in vehicles. A reduction in the number of parts in a vehicle is very valuable since it decreases costs and increases productivity. One area of vehicle design that has been particularly troublesome to modularize is the suspension system. Vehicle suspension systems are relatively complex in design and affect the overall ride and handling of the vehicle. Therefore, a reduction in suspension parts could have a decided impact on how the vehicle "feels" to a driver.
Jounce plates are commonly used in suspension systems and are disposed between a vehicle cross member and the suspension system to reduce jounce effects on the vehicle when a wheel is bounced up in the vertical direction. Jounce plates also help to reduce noise, vibration, and harshness that may be caused by the suspension. In an attempt to modularize the undercarriage of the vehicle, manufacturers have attached the engine cradle and suspension prior to installation on a cross member of the vehicle. This is accomplished by inserting a fastener through retention bores in the cradle isolator, suspension, and jounce plate.
In the past, up to four snap rings have been used to hold the fastener, cradle isolator, suspension, and jounce plate in place for shipping and subsequent attachment to the vehicle cross member on an assembly line. Unfortunately, the snap rings could cross thread with the fastener upon torquing as a result of the snap ring coming in contact with the threads of the fastener.
A method for mounting an engine is claimed in U.S. Pat. No. 3,694,895 (the '895 patent) to Werner. The engine mount shown in the '895 patent has a rubber bushing that overflows into a bolt retention cavity so that it comes in contact with a corresponding annular groove that is disposed on a bolt to hold the bolt within the cradle isolator. This is a limiting arrangement in that the use of special bolts that have annular grooves is required. This limits the length and the diameter of the bolt or fastener that can be used. Moreover, by allowing the oversized rubber bushing in the cradle isolator to "overflow" to come into contact with the bolt, tilting of the bolt from its axial center is prohibited so that it cannot extend through retention bores in the cross member, suspension, or jounce plate that may be slightly off centered due to body build variances. This greatly impedes installation time on the assembly line. A further limitation with the '895 patent is that torquing of the bolt would cause the rubber of the bushing to be pulled in to the bolt retention cavity thereby making torquing more difficult and weakening performance of the bushing. Thus, the nut must be torqued while the bolt remains stationary. This option is not available for retention systems that employ the use of a cage-nut assembly which wholly encases the nut upon installation.
It is therefore desirable in the art to have a fastener retention system employing the use of an oversized jounce plate that will retain the fastener, cradle isolator, jounce plate, and any associated washers in place without the need for a snap ring thereby eliminating cross-threading during decking on an assembly line. It is also desirable to have a cradle isolator that allows for slight tilting of the fastener thereby providing play for body build variations. It would also be advantageous to have an oversized jounce plate that can retain fasteners of various lengths and diameters.